Advantages of permanent magnet synchronous motors

1. Low loss and low temperature rise
Since the magnetic field of the permanent magnet synchronous motor is generated by the permanent magnet, it avoids the excitation loss caused by generating the magnetic field through the excitation current, that is, copper loss; the rotor runs without current, which significantly reduces the temperature rise of the motor, and the temperature rises under the same load. Increase or decrease by more than 20K.
2. High power factor
The power factor of the permanent magnet synchronous motor is high and has nothing to do with the number of motor stages. When the motor is fully loaded, the power factor is close to 1. Compared with the asynchronous motor, the motor current is smaller. Correspondingly, the stator copper loss of the motor is smaller and the efficiency is higher. . As the number of motor stages increases, the power factor of asynchronous motors becomes lower and lower. Moreover, because the power factor of the permanent magnet synchronous motor is high, the capacity of the power supply (transformer) supporting the motor can theoretically be reduced, and the specifications of the supporting switchgear and cables can also be reduced.
3. High efficiency
Compared with asynchronous motors, the efficiency of permanent magnet synchronous motors is much higher at light load. Its efficient operating range is wide, with an efficiency greater than 90% in the range of 25% to 120%. The rated efficiency of permanent magnet synchronous motors can reach 1 of the current national standard. Level energy efficiency requirements, this is its biggest advantage compared to asynchronous motors in terms of energy saving. In actual operation, the motor rarely operates at full power when driving a load. The reason is: on the one hand, when designers select motors, they generally determine the motor power based on the extreme working conditions of the load, and the chance of extreme working conditions occurring is very small. At the same time, in order to prevent burning under abnormal working conditions, If the motor is damaged, the design will further leave a margin for the power of the motor; on the other hand, in order to ensure the reliability of the motor, motor manufacturers usually leave a certain power margin based on the power required by the user. This results in that most of the actual operating motors operate below 70% of the rated power, especially when driving fans or pumps, and the motors usually work in the light load area. For asynchronous motors, their light load efficiency is very low, while permanent magnet synchronous motors can still maintain high efficiency in the light load area.
4. Other advantages
The permanent magnet synchronous motor also has the advantages of high starting torque, short starting time, and high overload capacity. It can reduce the installed capacity of the equipment drive motor according to the actual shaft power, save energy and reduce investment in fixed assets. The permanent magnet synchronous motor is easy to control, has a constant speed, and does not change with load fluctuations and voltage fluctuations. It is only determined by frequency, and operates smoothly and reliably. Due to the strict synchronization of rotation speed and good dynamic response performance, it is suitable for frequency conversion control. The installation dimensions of permanent magnet synchronous motors comply with IEC standards and can directly replace three-phase asynchronous motors. The protection level can reach IP54 and IP55. Some manufacturers also produce explosion-proof permanent magnet synchronous motors.